I've only seen them on their website, but Barclay Crocker has tube squeezers made out of both plastic and ceramic. Easiest way to find them is to click "toothpaste" on the left side of the site.
I found a vintage bag of them (1960s) at a resale shop. Aluminum, I think, but hefty enough to hold up to use. Am using a couple but have several extra. Let me know if you'd like one and I'll drop it in an envelope for you.
I don't use a key. It doesn't work as well with a metal tube but I hold both ends and use the corner of the counter to push the cream from the end to the front. I do the same with toothpaste.